noun

1. wild or violent mental disorder; specif., the manic phase of bipolar affective disorder, characterized generally by abnormal excitability, exaggerated feelings of well-being, flight of ideas, excessive activity, etc.
2. an excessive, persistent enthusiasm, liking, craving, or interest; obsession; craze a mania for dancing

Etymology: ME < LL < Gr, madness < mainesthai, to rage < IE base *men-, to think, be mentally excited > mind